1. Field of the Invention
The present invention relates to seeds, coated or impregnated with a Pink Pigmented Facultative Methylotroph (PPFM), which seeds have improved germinability. Also, the present invention relates to a method of producing zeatin using PPFMs.
2. Discussion of the Background
Improvements in crop yields is a highly active area of research, and as a result, today's farms are much more productive than their counterparts from a century ago. However, as the world's population increases with a concomitant decrease in farming resources, more and more emphasis is being placed on enhancing crop yields. Farmers are presently seeking ways to expand their yields while limiting the use of dangerous fertilizers and pesticides. An avenue of research which has developed from the desire to avoid harmful chemical crop treatments is the treatment of seeds or the soil with non-toxic crop augmenter prior to sowing.
Schroth et al, U.S. Pat. No. 4,849,008, describes enhancing root crop yields by treating plant seeds with a specific growth promoting bacterial strain of the genus Pseudomonas. The bacterial strains may be applied with a liquid carrier or in a paste.
Williams, U.S. Pat. No. 5,106,648, refers to a method of preparing coated seeds by slurrying seeds with a microorganism, which has a beneficial effect on plants which grow from these seeds, a carrier medium and an adhesive polymer. This method is supposed to maintain microorganisms viable for extended periods of time.
Mann, U.S. Pat. No. 4,061,488, addresses treatment of plant seeds with spores from Bacillus uniflagellatus to enhance plant growth. It is suspected that root growth triggers the germination of these spores.
The patents described above report enhancement of the growth of a plant, but do not address the problem of less than 100% seed germination. If a seed does not germinate, then no amount of plant growth improvement can be obtained. Low rates of germination are a problem with certain plant species in particular and with old seed in general. If a farmer were able to escalate the number of planted seeds which germinate, then an increase in crop production would be obtained. It is thus desirable to improve the germinability of seeds. Additionally, these references do not address addition of PPFMs to tissue cultures, for plant regeneration, embryo culture or rescue or propagation of cuttings or other propagules.
A further development in plant research is the use of cytokinins (e.g., benzyladenine or zeatin) to alter the growth and regeneration of plant cell cultures. Regulating the amount of cytokinin in a plant cell culture is necessary if regeneration of whole plants from the culture is desired. The ability to regenerate plants from cell culture develop new plant lines which may have novel physical characteristics such as pest resistance following gene transfer or mutagenesis by genetic engineering protocols.
Koulin et al, U.S. Pat. No. 4,977,087, depicts a method of regenerating plantlets from protoplasts cultured in liquid media containing cytokinins and/or auxins. Both zeatin and 6-benzyl-aminopurine (benzyladenine) are used in the culture media.
Mehra-Palta, U.S. Pat. No. 4,417,417, describes propagation of plantlets in the presence of a cytokinin (e.g. zeatin and 6-benzyl-aminopurine) and optionally an auxin.
Wright, U.S. Pat. No. 4,992,375, characterizes regeneration of soy bean plants using a nutrient medium containing a cytokinin (e.g. benzyladenine). Nodes used for regeneration were obtained by sterilizing soy bean seeds and germinating them in the presence of benzyladenine.
None of these references suggest the use of cytokinins as germination improvers. Additionally, PPFMs can be used advantageously in specific plant tissue culture processes. Further, zeatin is a costly chemical which cost has limited large scale use. It is thus desirable to find a novel method of producing zeatin.